Download The Paleozoic Era - Grass Range Science

The Paleozoic Era
By Reata and Cassidy
The Cambrian Period
● The Cambrian Period was the first time period of the
Paleozoic Era which lasted about 54 million years.
● During this time the continents had been joined in a single
supercontinent called Rodinia.
The Geological Conditions
Shallow seas spread over the landscapes, There was no continental
landmasses located at the poles.
Most continents were located in the southern hemisphere at low
paleolatitudes.
Rodina the large landmass that included all the continents on Earth, split to
form separate landmasses.
Climate Change
During the Cambrian there were no polar or high altitude glaciers.
Cambrian raised oxygen levels in Earth's atmosphere to approximately 10% of
that found in the modern atmosphere.
The Cambrian Earth likely had more equitable climates than present because
of the large amount of surficial seawater
The Cambrian had two great ice ages - the late Proterozoic and the Ordovician.
Plants and Animals
archaeocyathids and stromatoporoids (two extinct, sponge-like organisms
that formed reefs)
There was stromatolitic growth of blue-green algae and bacteria that covered
the rocks and formed sediment layers at near oceanic shorelines or lake
margins.
Primitive sponges and corals, simple pelecypods and brachiopods simple
molluscs, primitive echinoderms and jawless fishes, nautiloids, and a
diverse group of early arthropods
Ordovician Period
The Ordovician Period was the second out of six periods in the Paleozoic
Era.The Ordovician spans 41.2 million years from the end of the Cambrian
Period 485.4 million years ago.
From 460 to 450 Ma, volcanoes along the margin of the Iapetus Ocean
spewed massive amounts of carbon dioxide, a greenhouse gas, into the
atmosphere, turning the planet into a hothouse.
Geological Conditions
Rapid seafloor spreading at oceanic ridges fostered some of the highest
global sea levels in the Phanerozoic Eon.
The rate of seafloor spreading followed the breakup of the supercontinent
Rodinia near the end of the Proterozoic Eon.
Gondwana was a huge supercontinent during the Ordovician Period. It
contained the modern continents of Australia, Africa, Southern Europe,
Antarctica and South America
Climate Change
The large continent of Gondwana stopped its movement over to the south pole
which formed glaciers. Which cause the sea level to drop and the climate to
change.
Atmospheric carbon dioxide levels are believed to have been 8 to 20 times
their current values.
Plants and Animals
The cephalopods became the dominant predators of this period.
Along the edges of the water, groups of algae evolved into mosses and
bryophytes.
The orthoceras was a straight-shelled cephalopod that lived in the largest
open end of its shell.
Silurian Period
The Silurian Period follows the Ordovician Period in the Paleozoic Era. It began
around 443 million years ago and lasted for 26 million years.
As with other geologic periods, the rock beds that define the period's start and
end are well identified, but the exact dates are uncertain by several million
years.
Geological Conditions
The supercontinent Gondwana had drifted southward and covered most of the
southern latitudes.
The high sea levels of the Silurian and the relatively flat land resulted in a
number of island chains, and thus a rich diversity of environmental settings.
Climate Change
Early in the Silurian, glaciers retreated back into the South Pole until they
almost disappeared in the middle of Silurian.
Glaciers melted and warm shallow seas were created.
Because of this the climate was warm and tropical, the Earth entered a
greenhouse phase.
Plants and Animals
Because of the climate changes many warm shallow seas were created and
were an ideal environment for marine life.
Pentamerids and Silurian brachiopods had thicker shells, deeper bodies, and a
teardrop shape.
Jawless fish were abundant and had armor plated heads and bodies.
The Devonian Period
The Devonian period spanning 60 million years from the end of the Silurian,
419.2 million years ago.
By the middle of the Devonian, several groups of plants had evolved leaves
and true roots, and by the end of the period the first seed-bearing plants
appeared.
Geological Conditions
The Devonian period was a time of great tectonic activity.
The continent Euramerica (or Laurussia) was created in the early Devonian by
the collision of Laurentia and Baltica, which rotated into the natural dry
zone.
Sea levels were high worldwide, and much of the land lay under shallow seas.
Climate Change
The temperature gradient from the equator to the poles was not as large as it
is today.
The weather was also very arid, mostly along the equator where it was the
driest.
The climate would have affected the dominant organisms in reefs.
Plants and Animals
Among vertebrates, jawless armored fish (ostracoderms) declined in diversity,
while the jawed fish (gnathostomes) simultaneously increased in both the
sea and freshwater.
Early cartilaginous and bony fishes also become diverse.
Many Early Devonian plants did not have true roots or leaves like extant plants
and vascular tissue has yet to be observed in many of those plants.
Carboniferous Period
The Carboniferous is a geologic period and system that spans 60 million years
from the end of the Devonian Period 358.9 million years ago, to the
beginning of the Permian Period.
The name Carboniferous means "coal-bearing"
Mississippian
The Mississippian (also known as Lower
Carboniferous or Early Carboniferous) is a
subperiod in the geologic timescale or a
subsystem of the geologic record.
A period of marine ingression in the Northern
Hemisphere.
Pennsylvanian
The Pennsylvanian also known as Upper
Carboniferous or Late Carboniferous.
The younger of two subperiods (or upper of two
subsystems) of the Carboniferous Period.
All modern classes of fungi have been found in
rocks of Pennsylvanian age.
Geological Conditions
The Carboniferous was a time of active mountain-building, as the
supercontinent Pangaea came together.
The southern continents remained tied together in the supercontinent
Gondwana, which collided with North America–Europe along the present
line of eastern North America.
Climate Change
Early in the Carboniferous period, Earth’s climate was warm.
Glaciers formed at the poles, while equatorial regions were often warm and
humid.
Lack of growth rings of fossilized trees suggest a lack of seasons of a tropical
climate.
The thicker atmosphere due to Earth's faster rotation (a day lasted for 22.4
hours in early Carboniferous) created significantly stronger winds than
today.
Plants and Animals
The main Early Carboniferous plants were the horse-tails, scrambling
plants,club mosses, scale trees, ferns, seed ferns, and the Cordaitales.
Early Carboniferous plants were mostly preserved in coal balls
Most species of Carboniferous marine fish have been described largely from
teeth, fin spines and dermal ossicles, with smaller freshwater fish preserved
whole
Permian Period
The Permian spans 46.7 million years from the end of the Carboniferous
Period.
The Permian witnessed the diversification of the early amniotes into the
ancestral groups of the mammals, turtles, lepidosaurs and archosaurs.
Geological Conditions
During the Permian, all the Earth's major landmasses were collected into a
single supercontinent known as Pangaea
A new ocean was growing on its southern end, the Tethys Ocean, an ocean
that would dominate much of the Mesozoic Era.
Large continental landmass interiors experience climates with extreme
variations of heat and cold.
Climate Change
At the start of the Permian, the Earth was still in an Ice Age, which began in
the Carboniferous.
Glaciers receded around the mid-Permian period as the climate gradually
warmed, drying the continent's interiors.
In the late Permian period, the drying continued although the temperature
cycled between warm and cool cycles.
Plants and Animals
Permian marine deposits are rich in fossil mollusks, echinoderms, and
brachiopods.
Fossilized shells of two kinds of invertebrates are widely used to identify
Permian strata and correlate them between sites.
Primitive forms of dragonflies were the dominant aerial predators and
probably dominated terrestrial insect predation as well.
Reference
http://palaeos.com/paleozoic/cambrian/cambrian.htm
http://www.ucmp.berkeley.edu/cambrian/cambrian.php
https://www.reference.com/science/were-major-geological-events-cambrianperiod-42a98f0ddaa2641d
http://www.encyclopedia.com/earth-and-environment/geology-andoceanography/geology-and-oceanography/cambrian-period
http://www.fossils-facts-and-finds.com/ordovician_period.html